KansasMike posted:In my neighborhood the KCS uses a lot of DP, especially on coal and grain trains. The odd part is that one coal train may run with 2 on the head and 3 on the rear and the next one may be 2 on the head, 2 about 2/3 back and 1 on the rear. I haven't had a chance to talk with anyone that would know (actual railroad employee) and ask why one coal train runs 3 x 2 or 2 x 3 and the next one is 2 x 2 x 1.
Don't know about KCS, but here in the Orange Kingdom I see BNSF shuttle trains (ethanol, grain) with engines on both ends. Usually it's 3/2 or 2/3 but it can be 1/3 or 3/1. I think what you're missing is these trains aren't uncoupled--they are unit trains. Train pulls empty hoppers to the elevator (usually a big circle track), loads the grain, and simply hops into the cab at the other end of the train and takes it back on the line it came in on.
